A federal judge has thrown out government safety findings on one of America’s most common farm pesticides, ruling that wildlife officials used data so badly flawed it couldn’t support their conclusion that the chemical posed no risk to endangered species.
U.S. District Judge Edward Chen of the Northern District of California ruled Tuesday that the Fish and Wildlife Service relied on contaminated data sets when it determined chlorpyrifos — used on everything from almonds to corn — wouldn’t harm threatened plants and animals across the country.
The pesticide has been at the center of a decade-long fight between agriculture interests and environmental groups. Chlorpyrifos is sprayed on crops covering millions of acres, making it critical to commercial farming operations. But the chemical has also been linked to neurological damage in children and banned from household use since 2001.
Chen’s 89-page ruling found the agency’s biological opinion “arbitrary and capricious” — legal language meaning the government failed to follow basic requirements of reasoned decision-making. The judge pointed to multiple instances where federal scientists appeared to cherry-pick data that supported approval while ignoring contradictory evidence.
The case was brought by the Center for Biological Diversity and Pesticide Action Network, which challenged the Fish and Wildlife Service’s 2020 finding that chlorpyrifos use wouldn’t jeopardize 1,778 endangered species. That conclusion allowed the Environmental Protection Agency to keep the pesticide on the market despite mounting health concerns.
Chen specifically faulted the agency for using industry-funded studies without adequate scrutiny and for failing to account for how the chemical accumulates in waterways where endangered salmon spawn. The ruling noted federal scientists dismissed peer-reviewed academic research showing harm while accepting less rigorous data from pesticide manufacturers.
The decision sends the case back to the Fish and Wildlife Service for new analysis. During that review, which could take years, chlorpyrifos remains legal for agricultural use in most states. California banned it in 2020, and several other states have imposed restrictions.
Farm groups warned the ruling could force growers to switch to more expensive or less effective alternatives during a period of already-thin profit margins. Environmental advocates said the decision proves federal agencies have been putting chemical industry interests ahead of public safety and wildlife protection.
The Fish and Wildlife Service has not announced whether it will appeal. The agency must now decide whether to defend its original findings or conduct the comprehensive safety review environmental groups have demanded since 2016.
Key Points
- Federal judge found Fish and Wildlife Service used contaminated data to clear chlorpyrifos pesticide, calling the agency’s work “arbitrary and capricious”
- The 2020 approval covered 1,778 endangered species and allowed continued use of the chemical on millions of acres of farmland despite health concerns
- Case returns to federal wildlife officials for new review, but pesticide remains legal during what could be years of additional study
https://www.courthousenews.com/judge-says-feds-used-faulty-data-to-support-pesticide-findings/ – May 14, 2026
